To determine whether the MUC1–PP2A axis functions across other SCLC subtypes, we investigated phosphorylation levels of PKCζ and NUMB in cell lines representing distinct subtypes–NCI‐H69 (SCLC‐A), NCI‐H526 (SCLC‐P) and NCI‐H82 (SCLC‐N). Here, NUMB is linked to small cell lung carcinoma.